As municipal sewer systems age, particularly those utilizing clay pipe and the like, the deteriorating pipe frequently undergoes partial collapse along its length. These collapses allow dirt, rock and other debris to enter into the pipe, impeding the flow of fluid or effluent through the sewer pipe. If a significant collapse occurs, the sewer pipe may become totally blocked. In addition, such breakage permits sewage to leak out into the surrounding ground, resulting in potential contamination of ground water and the like.
Because clay sewer pipe has been installed in large parts of the country, the deterioration of such pipe increasingly is becoming a problem for many municipalities. Where the pipe is so badly collapsed and damaged that it must be replaced, new trenches frequently are dug down to the broken pipe, it is removed, and new pipe is laid. The trenching operation is expensive and highly disruptive of the surrounding ground surface under which the clay sewer pipe has been laid. Frequently, the ground surface is covered with a roadway. In such a case, digging a trench from the surface to the pipe to lay a new sewer .line or new sewer pipe damages the road, which must be repaved.
Efforts to rehabilitate old deteriorating clay pipe sewer lines have been devised for relining the deteriorating sewer lines with new pipe. Current techniques employ the slip lining of sewer lines with high density polyethylene pipe. Such polyethylene pipe is flexible and, consequently, follows the lay of the land. An important characteristic of such pipe is that it can be cold-bent to a radius of twenty to twenty-five times the pipe outside diameter; so that it may be used to negotiate relatively sharp curves.
A technique, which currently is used to reline clay sewer lines, is to dig a relatively large hole down to the sewer pipe which is to be relined. This hole typically is located no more than forty to sixty feet from a manhole cover (or up to two hundred feet if the old line is reamed out first), which provides access to the sewer pipe. The sewer pipe is broken open over a relatively long length in the hole which has been dug (typically one foot per inch of nominal diameter of the liner to be inserted). The liner pipe then is inserted into the broken-open existing sewer pipe through an entrance slope, which typically is 2:1 or flatter. A pulling line, in the form of a cable, is threaded from a winch truck, through the manhole and around a pulling assembly located in the bottom of the manhole and into the open end of the pipe. A pulling head on the line is attached to the forward end of the polyethylene liner pipe to be inserted into the sewer line. Once this is done, continuous lengths of the polyethylene pipe (connected together by heat fusion) are pulled by the pulling line through the existing sewer pipe. If any substantial amount of dirt, obstructions or broken pieces of the existing sewer pipe are encountered, the pulling head frequently becomes jammed or stuck. When this occurs, a new hole must be made at the point where the head is stuck, and steps must be taken to clear the broken pipe; so that the polyethylene liner pipe can be pulled the full length through the hole. While this system theoretically appears sound, it is one which in fact frequently encounters the obstructions noted above, and is inefficient and costly. To the extent that the underlying sewer pipe is not seriously damaged, this system, however, does permit substantial lengths of liner pipe to be pulled through existing pipe without disturbing the surface. If the underground clay pipe, however, is badly deteriorated, it often is faster and less expensive to trench the entire length from above ground and lay new pipe in a conventional manner.
The U.S. patent to Winkle U.S. Pat. No. 4,930,542 is directed to a system for restoring underground pipe. The Winkle system uses an expander/piercer head, which is pushed through the existing pipe on a section-by-section basis. The expander is operated to press outwardly the existing pipe and any earth which may have fallen into it. The expander then is retracted and moved to the next position. When it is moved to the next position, a short segment of liner pipe is pushed into the pipe behind the expander/piercer head. This step-by-step operation is continued until the length of pipe to be repaired has been fully lined with the individual liner pipe segments. In order to operate this device, it is necessary to have access to the pipe which is being repaired through a manhole or the like.
Because of the manner in which the hydraulic portions of the Winkle system operate, it is necessary to supply substantial force to the site of the manhole opposite the opening into which the piercer and the pipe segments are inserted. No curvature of any of the parts takes place in this system. There also is no boring and removal of material through the liner pipe in the operation of this system. The debris is pressed forward as the new pipe is inserted into the damaged or pre-existing sewer pipe. Obviously, if large amounts of debris are accumulated, the expander no longer can be pushed forward. When this occurs, it is necessary to dig a hole down to the point where the blockage occurs, clear the blockage, and then resume operation.
Other patents, which are directed to the insertion of liners into existing pipes, include the U.S. patents to Barber U.S. Pat. Nos. 4,207,130; Long 4,668,125; and Fujii 5,101,863. In the lining systems disclosed in these patents, the liner is pushed into the pipe. In the device of the Long patent, the pipe first is cleaned through a separate operation. After the pipe has been cleaned, the liner tube is pushed into the pipe. Liner tube is pushed into the pipe in the devices disclosed in Barber and Fujii. In neither of these patents, however, is there any provision for clearing obstructions from the existing pipe prior to or during the insertion of the liner. As a result, if large amounts of debris or serious breakage in the existing pipe is present, it will be necessary, with these systems, to dig down to the existing pipe, break it open and remove the obstruction before the insertion of the new liner pipe can be completed.
Other systems, in which the liner pipe is pulled into the main pipe, as described above, are described in the U.S. patents to Storah U.S. Pat. Nos. 4,777,984; Putter 5,060,696; Rockower 5,171,106; Moriarty 5,173,009; Torielli 5,192,165; and Gargiulo 5,213,727. Since all of these patents require a pulling of the liner into the main pipe, access entirely through the length of pipe to be relined must be available for the insertion of the pulling cable, prior to connecting it to a pulling head the end of the pipe being pulled. In some of these patents, the pipe either is expanded or broken open prior to the pulling of the liner through it; but in no case is there any boring of the pipe, or simultaneous removal of the debris through the liner as it is placed in the pipe.
It is desirable to provide a pipe relining system and a pipe laying system, which overcomes the disadvantages of the prior art noted above, which is simple and effective in operation, and which operates to push the pipe or liner pipe through the ground or existing pipe to be relined.